Yes, each time you load a game you start a diplomacy event for the AIs. When at that time of the game one AI is very convinced that it is a good idea to start a war there is nothing you can do about it
Another disadvantage is that they gain additional technology trade which can make it very hard to keep track in the technology race.
The third thing Brad just mentioned on the GC2 site is that the AI gets an additional strategy calculation. i.e. not an additional turn but sometimes they react a bit smarter.